Drug-eluting stents are small scaffolds made of wire that are inserted into the narrowed coronary arteries of patients with atherosclerosis. The stent helps to hold the artery open and also releases a drug that prevents any further blockage or obstruction occurring in the artery. The stent placement is carried out in a procedure called coronary angioplasty.
History and approval of drug-eluting stents
Before drug-eluting stents were available, bare metal stents that did not contain any drugs were used to open up arteries. However, several clinical trials showed that drug-eluting stents were superior to bare-metal stents in preventing coronary artery narrowing. They were associated with lower rates of adverse cardiac events such as heart attack and repeat intervention due to re-narrowing or restenosis of the artery.
Before the advent of angioplasty, blocked coronary arteries were treated using a procedure called cardiopulmonary bypass surgery. In 1977, Andreas Grüntzig developed the procedure of percutaneous transluminal coronary angioplasty (PTCA) or balloon angioplasty, which involved a balloon being inflated within the artery to keep it open. Although balloon angioplasty was a relatively safe procedure, restenosis rates were still fairly high and seen in nearly 30% to 40% of patients within the first year after PTCA.
In 1986, the first stent placement was performed by Puel and Sigwart, who developed the bare metal stent. The stents reduced restenosis rates by acting as a scaffold that could keep the artery held open. Although the stents reduced restenosis rates, narrowing did still occur due to the formation of scar tissue in the lining of blood vessels. This led to the development of stents that eluted a drug that could minimise the growth of neointimal tissue.
Sirolimus was one of the first drugs to be used in these stents and the sirolimus-eluting Cypher(R) stent was approved in 2003 by the United States Food and Drug Administration (FDA).